The present study examines the current scientific findings about the complex physiology of bitter taste perception. Several mechanisms for transduction of bitter compounds were found: the interaction with G-proteine coupled receptors with subsequent activation of phosphodiesterase and phospholipase C respectively, the direct activation of the G- protein without involvement of any receptor, the direct increase of intracellular calcium stores, the interaction with enzymes of the signal

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... n cascade, and the blocking of potassium channels. Using one or more of these mechanisms, bitter compounds can cause depolarization of sensory cells, which generates an electric signal transferred to the brain. Of the 39 existing genes for Tas2R- receptors only 24 or 25 are operating, the remaining 14 or 15 are pseudogenes. These 24 (25) Tas2R- receptors are able to detect thousands of structurally different bitter tasting chemicals. For 13 human and murine Tas2R- receptors the ligands are already known or at least suspected. Common inhibitors of bitter compounds are the riboflavin binding protein (RBP) and several sodium salts. Pharmaceutical and food industry are investigating busily for further inhibitants. Rodgers´ PGLT (phylogenetic- like- tree) classifies known bitter compounds regarding their chemical structures. This information can be used to further investigate which structural components are involved in creating bitter taste. Lactone rings were found to be present in numerous bitter molecules. Existing data about PROP/PTC tasters, nontasters, and supertasters evidence that these three groups vary significantly in their experience of taste. But there are also genetical differences in other bitter taste receptors, for example the receptors of caffeine, saccharine, and salicine. These factors certainly do have influence on nutritional habits. That is why they are so important for nutritional sciences.